This invention relates generally to the lining of pipelines and passageways using tubular liners which are of a nature such that when they are inserted into the pipeline or passageway they are flexible in nature and can therefore be inflated to conform with the pipeline or passageway surface, but which are in fact of a type containing curable synthetic resin which is caused to cure to a hard condition when the liner is held to the passageway surface so that eventually when the resin cures, the lining will form a hard passageway lining pipe.
The lining tube may typically comprise a layer or layers of resin absorbent material such as fibrous felt or layers of glass fibre matting which soaks up the resin when applied, to give the lining tube a certain amount of bulk and thickness so that in effect a hard lining pipe will eventually be formed. The said layer or layers is or are usually surrounded initially by an impermeable film or coating, which is usually a coating bonded to the layer of fibrous material or the outer layer of fibrous material.
The general process outlined above has been practiced by the assignee herein for many years and on a highly successful basis. The lining tubes are marketed under the trademark "Insitutubes" (registered trade mark) and the cured lining pipes are marketed under the trademark "Insitupipes" (registered trade mark)
We have previously proposed that the lining tube may be inserted by connecting to one end of same what is referred to as a preliner which is a tube made from flexible material such as woven fabric or a plastic film, and which is applied to the pipeline or passageway surface to line same before the lining tube is inserted, hence the name preliner. Also, to the other end of the lining tube is attached an inflation tube which may be of a like material to the preliner, but which is used to inflate the lining tube, when it is in position, by being everted, by using fluid pressure, into the inside of the lining tube. The fluid used may be gaseous or liquid, but in either event the inflation tube inflates the lining tube up into conforming configuration with the pipeline or passageway surface where it is held until the resin is cured either naturally, or by forced curing involving the application of heat or light (when the resin is a light cure resin).
This method of installing the lining tube has become known by the description "triple inversion". The method involves everting the preliner into the pipeline or passageway using fluid pressure, which has the effect of pulling the lining tube into the pipeline or passageway until it reaches at the desired position, and then the inflation tube is everted into the inside of the lining tube to inflate same.
The method which was used previously for inserting the lining tube was simply to evert same into the pipeline or passageway using fluid pressure.
The "Triple Inversion" method has been developed to enable the cured lining pipes to be made with no entrapment of air in the resin/felt during inversion and this is very successful but is expensive in that a coating is needed on the outside as well as on the inside and the installation takes longer than a single inversion method. An alternative method of achieving the same object is to trap a slug of resin against the everting face with a rolling pig. For pipelines with lateral connections, manholes, etc. it is necessary to use a strong preliner to contain the pig and resin. This method has been demonstrated successfully. The invention disclosed herein achieves the same effect without the need for a rolling pig filling the pipeline.